Resonant line oscillator



J. L; CLARK RESONANT LINE OSCILLATOR Sept. 22, 1953 Filed Jan. 29, 1946 FlG.l

FIG.3

1 INVENTOR JAMES L. CLARK ATTORNEY FIG.2

Patented Sept. 22, 1953 RESONANT LINE OSCILLATOR James L. Clark, Chicago, Ill., assignor to the United States of America as represented by the Secretary of War Application January 29, 1946, Serial No. 644,169

6 Claims.

This invention relates generally to electrical apparatus and in particular .to resonant line oscillators.

In the prior art, oscillators or generators often used in the ultra-high frequency range comprise a pair of thermionic tubes connected in a pushpull tuned-plate tuned-grid circuit, in which a first resonant transmission line is coupled between the anode electrodes and a second resonant transmission line is coupled between the grid or control electrodes. The lines may include short-circuiting members for tuning purposes. The frequency range of such a generator may be extended by placing an inductance in parallel with each resonant circuit, permitting the generation of higher frequencies. Such inductances may each be of strap form for use in ultra-high frequency oscillators, and may be termed backlines.

It is an object of this invention to provide simple means for increasing the operating frequency range of a resonant line oscillator.

It is a further object of the invention to provide a simple structure which permits ready connection or removal of an inductance between terminal pins of thermionic tubes.

Other objects, novel features and advantages of this invention will suggest themselves to those skilled in the art and will become apparent from the following description of the invention taken in connection with the accompanying drawing in which:

Fig. 1 is a front view showing a structure embodying the principles of this invention;

Fig. 2 is a side view of Fig. 1; and

Fig. 3 illustrates the equivalent electrical circuit of which the structure shown in Figs. 1 and 2 forms a part.

Referring now more particularly to Figs. 1 and 2, the high-frequency tubes V1 and V2 are each of the double-ended doorknob type, which has two terminal pins at opposite ends of the tube for its grid, and also two terminal pins for its plate. Terminal pins (not shown in Fig. 1 or 2) are also provided at opposite ends of each tube for the cathodes thereof. The tube pins I and II, I2 and I3, are connections to the plate electrodes of tubes V1 and V2, respectively, as shown. Pins 52' and. I3 are connections to the grid electrode of tube V2 and the pins I0 and II, hidden from view in Figs. 1 and 2, are connections to the grid electrode of tube V1. Tubes V1 and V2 may be mounted upon a chassis or base board I4 by means of bearing block structures i5 as shown. Two backlines or conductive straps I6 and I6 are mounted at their centers upon an insulating support I1, and in the: circuit here" other end of strap I6 for engagement with pin.

Ii. Blocks 26, preferably of insulating material, are provided to maintain straps I6 and I6 and the clips thereon away from the pins that. These blocks each have: an open jaw across which extends a removable: are. adapted to be withdrawn, so that when the clip: ends of straps I6 and I6 are disengaged from. the tube pins, the straps I6 and I6 may be they normally engage.

thumbscrew member 22. Members :22

drawn into the jaws of blocks 26 and the thumbscrew members 22 reinserted in blocks 20 to re-- tain the straps and clips in their disengaged po-- sition. In Fig. 1, the broken line position of.

strap I6 shows it connected to the plate of tube V2 by engagement of clip I8 with pin I3.

The manner in which the straps I6 and I6" function to increase the operating frequency of the oscillator circuit will become apparent by reference to Fig. 3, wherein is diagrammed a substantially equivalent lumped-constant circuit in a conventional manner. Certain parts in the diagrammatic representation of Fig. 3 are numbored to correspond to like parts in Figs. 1 and 2. Thus straps I6 and I6 are here represented as effective inductances. With these backlines I6 and I6 in parallel, respectively, with the equiva lent tuned circuits connected between terminals I3 and I2, and I0 and I2, the eifective inductance in each tuned circuit is decreased, resulting in a higher operating frequency.

When the connections at II, II, I3 and I3 are broken (paralleling straps I6 and I6 removed), the oscillator covers a lower frequency range.

Although the embodiment described herein employs a resonant line oscillator and doubleended doorknob type tubes, the invention may be applied to many other tubes and circuits. Therefore, while there has been described what is at present considered to be a preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the scope and spirit of the invention as set forth in the appended claims.

What is claimed is:

1. In a high frequency electrical apparatus, the combination including a first and a second vacuum tube, each having at least a plate and a grid, each plate and each grid having at least one terminal pin, two inductances in the form of flexible conductive spring straps each having at its ends means for contacting said pins, insulating means supporting said metal straps at theirmidpoints, said tubes and straps being so iposiir tioned that one said strap may be connected between the plate terminals offsaid tubes and-the other said strap may be connected between the grid terminals of said tubes, and removable retaining means to hold the ends of said straps out of contact with said pins when said straps are disconnected from said pins.

2. In a high frequency electrical apparatus, thecombination including a first and asecond vacuum. tube each having at leasta plate and a grid, each. plate and each grid having at least one terminal pin, two inductances in the form of conductivespringstraps-and means at their ends for contacting said pins,.said tubes-and straps being so positioned that one said strap; may beconnected betweenthe plate terminals of said tubes and the other 'sai d strap may beconnected be tween the grid terminals of said tubes, and re- 4.' In a highufrequency electrical apparatus having at least one tuned circuit and two terminals connected to opposite ends thereof, means for varying the resonant frequency of said tuned circuit, said means including an inductance in the form of a resilient conductive spring strap so mounted and positioned that its ends normally contact said two terminals, and retaining means for optionally holding the ends of said strap out of contact with said terminals.

5. A radio frequency oscillator comprising a first and second vacuum tube, each tube having at least a plate and a grid, each plate and grid having at least two terminal pins, a tuned circuit connected between a terminal pin of each of said plates, a tuned circuit connected between a terminal pin of each of said grids, two inductancesinthe-formof flexible conductive spring straps each being mounted to have its ends normally contacting the other terminal pins of said plates and grids respectively, and retaining meansfor holding the ends of said straps out of contact with said other terminal pins when said straps are disconnected from said terminal pins.

6. An osci1lator in accordance with claim 5 in which: each of said straps is fixedly mounted at its center with each of its ends normally incontact with one of said terminal pins and'said retaining means include a pair of adjustable screws mounted at fixed points adjacent said terminal pins, said screws in one position; holding said straps out-of-contact with said terminal pins and in another position being out-of-contact with said straps whereby said straps contact said terminal pins.-

JAMES L. CLARK.

References Cited in the file of this patent UNITED" STATES PATENTS Number Name Date 2,186,434 Senauke Jan. 9, 1940 2,298,075 Tinus Oct. 6, 1942 2,325,174 Cooper July 2'7, 1943 2,391,917 Newkirk Jan. 1, 1946 2,410,222 Lawrence Oct. 29, 1946 2,414,280 Thomas Jan. 14, 1947 

